Sociality and Social Behaviour (Part 2). Altruism by non-relatives Reciprocity - incur a cost now in anticipation of receiving a benefit later Modelling.

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Presentation on theme: "Sociality and Social Behaviour (Part 2). Altruism by non-relatives Reciprocity - incur a cost now in anticipation of receiving a benefit later Modelling."— Presentation transcript:

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Altruism by non-relatives Reciprocity - incur a cost now in anticipation of receiving a benefit later Modelling - use Game Theory - John Nash

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Altruism by non-relatives Prisoner’s Dilemma 2 prisoners - caught and jailed for a petty crime - suspected of having committed a more serious crime

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Altruism by non-relatives Prisoner’s Dilemma Each prisoner (player) has a choice cooperate - deny all knowledge of the serious crime defect - accuse the other of the more serious crime Reward for defecting - forgiven minor crime

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Altruism by non-relatives Prisoner’s Dilemma How should they behave? After a number of simulations with more than one move, Best strategy is a tit-for-tat -cooperate on first move and then do what opponent did on previous move

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Altruism Reciprocity - in predator detection Meerkats - sentinels This behaviour is adaptive if: Chance of being preyed on while acting as a sentinel Survivorship while others are sentinels <

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Altruism Reciprocity - in predator detection But is this really reciprocity? Alternative hypothesis (selfish): “Sentinels” are really just animals who have finished feeding and are looking for predators to protect themselves.

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Altruism But is this really reciprocity? Some predictions from reciprocity hypothesis: PredictionObservation Regular rotation of sentinel duty Sentinel duty appears to be haphazard Sentinel duty has risk of succumbing to predator Sentinels are usually closer to an escape burrow No difference in sentinel time when solitary Less time is spent in predator detection in groups